What is the treatment for disseminated Varicella-Zoster Virus (VZV) with symptoms of right arm and shoulder pain, numbness, and a vesicular rash on the chest and upper back?

Treatment of Disseminated Varicella-Zoster Virus (VZV)

Intravenous acyclovir 10 mg/kg every 8 hours is the treatment of choice for disseminated VZV infection, and should be initiated immediately given the high mortality risk in immunocompromised patients. 1

Immediate Management

Start IV acyclovir without delay at 10 mg/kg every 8 hours (some sources suggest 5-10 mg/kg range, but 10 mg/kg is preferred for disseminated disease). 1, 2

• The presentation described—vesicular rash on chest/upper back with arm/shoulder pain/numbness—suggests dermatomal involvement with possible dissemination beyond a single dermatome. 1
• Disseminated VZV lesions characteristically begin on face and trunk, then evolve peripherally, with lesions in varied stages of progression appearing simultaneously. 1
• Do not use oral antivirals (valacyclovir, famciclovir, or oral acyclovir) for suspected disseminated disease—oral therapy should be reserved only for mild cases in otherwise healthy hosts or to complete therapy after clinical response to IV treatment. 1, 3

Treatment Duration and Monitoring

• Continue IV acyclovir until clinical improvement occurs, typically 7-14 days minimum, then consider switching to oral therapy to complete the course. 1, 2
• In immunocompromised patients, lesions may continue to develop over 7-14 days and heal more slowly, requiring prolonged IV treatment. 1, 2
• Monitor closely for visceral dissemination (hepatitis, pneumonitis, encephalitis) and secondary bacterial or fungal superinfection, which can complicate chronic ulcerations. 1, 2

Adjunctive Measures

If the patient is on immunosuppressive medications, temporarily reduce or discontinue them while maintaining antiviral therapy. 3, 2

• Immunosuppression may be cautiously restarted after skin vesicles have resolved and the patient has been on adequate anti-VZV therapy. 2
• Blood VZV-DNA PCR may help establish diagnosis of disseminated infection, particularly when presentation is atypical or precedes rash appearance. 1, 4

Special Considerations for V1 Distribution

Given the right arm/shoulder involvement, assess for V1 (ophthalmic) distribution:

• Obtain ophthalmology consultation if there is any suggestion of ocular involvement (periorbital lesions, eye pain, vision changes). 3
• V1 herpes zoster carries significant risk of ocular complications requiring specialized management. 3

Dosing Adjustments

• Adjust acyclovir dose for renal impairment—monitor renal function frequently as acyclovir can be nephrotoxic. 1
• Ensure adequate hydration to prevent acyclovir-induced crystalline nephropathy. 1

Common Pitfalls to Avoid

• Do not delay treatment waiting for confirmatory testing—initiate IV acyclovir based on clinical suspicion alone. 1, 2
• Do not undertreat with oral antivirals—this is a critical error in disseminated or potentially disseminated disease. 1, 3
• Do not assume localized disease based on initial presentation—dissemination can occur rapidly, particularly in immunocompromised hosts where 10-20% of dermatomal zoster progresses to dissemination without prompt antiviral therapy. 1
• Mortality from disseminated VZV in immunocompromised patients can be as high as 55% without appropriate treatment. 4

Acyclovir-Resistant Cases

If the patient fails to respond to standard IV acyclovir after 7-10 days of therapy, consider acyclovir resistance:

• Switch to foscarnet 40 mg/kg IV every 8 hours, as acyclovir-resistant VZV is also resistant to other nucleoside analogs. 2